There was fit-again Robin van Persie, ready to hit the heights again after a frustrating series of injuries. There was Radamel Falcao , who jetted in just before the end of the transfer window to great excitement. There was the ever-reliable Wayne Rooney, rested and recuperated after England's early exit from the World Cup. And there was James Wilson, ready to kick on after breaking into the first-team picture.

Things didn't quite go to plan, of course. Van Persie struggled for form and fluency. Wilson's progress was slower than some had expected. Rooney spent half the season playing in central midfield. Falcao... well, we all know how that went.

Whether or not the former Arsenal man leaves, it seems certain that Louis van Gaal will seek to boost his attacking ranks this summer. Here, then, are six of the leading contenders for the number nine jersey:

Karim Benzema

The dream ticket . He may have operated in Cristiano Ronaldo's shadow for the last few years, but the Frenchman is a rare talent, capable of individual fireworks but also willing to work for the benefit of his team-mates.

(Image: Angel Martinez)

Benzema has been remarkably consistent in front of goal, averaging over 23 goals per season in all competitions over his last eight campaigns for Real Madrid and Lyon. But there have also been countless assists, not to mention unselfish runs to create space for others.

Edinson Cavani

Seemingly linked with every club in the world over the last couple of seasons, Cavani continues to be an attractive proposition for Europe's elite. Dogged, talented and eminently marketable (look at those cheekbones!), the Uruguayan has star quality that not many can match.

(Image: EPA/IAN LANGSDON)

There are question marks, however. The first is over his goalscoring record. After three exceptional seasons at Napoli, his haul at Paris Saint-Germain has been less impressive – although admittedly he has often had to play wide in support of Zlatan Ibrahimovic.

Secondly, PSG may not be quite so willing to sell as they appeared to be six months or a year ago. With Ibrahimovic's days in France numbered, they would surely be loath to let go of their only other out-and-out striker. Cavani's late-season flurry (13 goals in his last 11 games of the season) may just have made him indispensable.

The issue for United would be style: Mandzukic – much like Radamel Falcao – thrives on swift, aerial service. With Louis van Gaal favouring a more measured, cautious approach, the former Wolfsburg striker would likely be a square peg in a round hole. Plus, at 29, he's no spring chicken.

Suitability : 3/10 Likelihood : 5/10

Harry Kane

Having gone from substitute to superstar in little more than six months at Spurs, it comes as little surprise that Kane is now being linked with a move to Old Trafford . Manchester United are never averse to nabbing the Premier League's best emerging talent, after all (cough cough Ashley Young cough).

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That Kane had an impeccable season cannot be denied. With his barreling runs and pinpoint shooting, he terrified defences the country over during that springtime purple patch and ended the season with 31 goals in all competitions. The fact that he already knows the league would be a big bonus for United, as would his tender age.

Potential issues? There must be a slight worry that he will be unable to strike gold twice – that part of his success was down to the fact that he was such an unknown quantity. Plus there is the Daniel Levy factor, which means he wouldn't come cheap.

Suitability : 7/10 Likelihood : 6/10

Carlos Bacca

Flying under the radar at Club Brugge just three years ago, the Colombian hitman has become one of Europe's most in-demand forwards on the back of two fine seasons for Sevilla. A confident, instinctive finisher, Bacca has hit 49 goals since making the switch to Spain, helping his side to two Europa League titles on the bounce.

(Image: Michael Steele)

Sevilla may be willing to cash in on the 28-year-old, for whom they paid a measly €7million. The question for Van Gaal will be whether Bacca is a rounded enough player to become the focal point of the United attack. As Falcao's travails proved, finishing ability alone is not enough.

Suitability : 5/10 Likelihood : 6/10

Gonzalo Higuain

A long-term darling of the Arsenal transfer fanboys, Higuain could now be on the market after Napoli failed to secure a Champions League spot on the final day of the Serie A season.

(Image: Getty Images)

Ironically, that was in large part down to Higuain, who missed the penalty that would have given the Partenopei the lead in the de facto play-off with Lazio. But the Argentine still did more than most to boost his side's chances (netting two in that game and 29 in all competitions over the course of the season) and will surely feel he deserves to be playing in Europe's top competition.

Like Benzema, he only played a supporting role at Real Madrid but is one of the most ruthless finishers around and, at 27, appears to be reaching his prime. Just don't let him take penalties.